How to calculate with html form select and option in php - php

Question

A form that takes a lot of information from the user and processes it, and finally a number is displayed.
A number of objects are obtained according to other objects.
index.php
<form action="calc.php" method="POST">
<select name="NumberOfPeople2">
<option value="1">1</option>
<option value="2">2</option>
</select>
<select name="NumberOfBathTimes">
<option value="1">one</option>
<option value="2">two</option>
</select>
<select name="DurationOfBathing">
<option value="10">10 min</option>
<option value="20">20 min</option>
</select>
<input type="submit" value="submit">
</form>
calc.php
<?php
include 'include/calc.inc.php';
$NumberOfPeople = $_POST['NumberOfPeople'];
$NumberOfBathTimes = $_POST['NumberOfBathTimes'];
if($_POST['DurationOfBathing']=='10')
{
$DurationOfBathing='60';
}
if($_POST['DurationOfBathing']=='20')
{
$DurationOfBathing='100';
}
if($_POST['NumberOfBathTimes']=='1')
{
$FactorUseBath='0.14285714';
$FactorNumberBath='1.2';
}
if($_POST['NumberOfBathTimes']=='2')
{
$FactorUseBath='0.28571429';
$FactorNumberBath='1.2';
}
$ConsumptionBath = new Calc($NumberOfPeople,$DurationOfBathing,$FactorUseBath,$FactorNumberBath);
echo $ConsumptionBath->calcMethod();
calc.inc.php
<?php
class Calc{
public $NumberOfPeople;
public $DurationOfBathing;
public $FactorUseBath;
public $FactorNumberBath;
public function __construct($NumberOfPeople,$DurationOfBathing,$FactorUseBath,$FactorNumberBath){
$this->NumberOfPeople = $NumberOfPeople;
$this->DurationOfBathing; = $DurationOfBathing;
$this->FactorUseBath; = $FactorUseBath;
$this->FactorNumberBath; = $FactorNumberBath;
}
public function calcMethod(){
$result = $this->DurationOfBathing*$this->FactorUseBath;*$this->FactorNumberBath*$this->NumberOfPeople;
return $result;
}
}
All objects obtained must be multiplied.
The answer is $ConsumptionBath
Is this the right way?

Answer 1

This is right way, but you should declare each and every variable somewhere which is used in script. For example, in your given script, variable $DurationOfBathing is initialised only in if conditions and will give undefined variable error in case if conditions fails. So I've updated code below:
include 'include/calc.inc.php';
$NumberOfPeople = $_POST['NumberOfPeople'];
$NumberOfBathTimes = $_POST['NumberOfBathTimes'];
$DurationOfBathing = $FactorUseBath = $FactorNumberBath = '';
if ($_POST['DurationOfBathing'] == '10') {
$DurationOfBathing = '60';
} else if ($_POST['DurationOfBathing'] == '20') {
$DurationOfBathing = '100';
}
if ($_POST['NumberOfBathTimes'] == '1') {
$FactorUseBath = '0.14285714';
$FactorNumberBath = '1.2';
} else if ($_POST['NumberOfBathTimes'] == '2') {
$FactorUseBath = '0.28571429';
$FactorNumberBath = '1.2';
}
$ConsumptionBath = new Calc($NumberOfPeople, $DurationOfBathing, $FactorUseBath, $FactorNumberBath);
echo $ConsumptionBath->calcMethod();
Update
There is some problem in class as well. Some extra semi colons ; are added there. Use this updated code:
<?php
class Calc {
public $NumberOfPeople;
public $DurationOfBathing;
public $FactorUseBath;
public $FactorNumberBath;
public function __construct($NumberOfPeople, $DurationOfBathing, $FactorUseBath, $FactorNumberBath) {
$this->NumberOfPeople = $NumberOfPeople;
$this->DurationOfBathing = $DurationOfBathing;
$this->FactorUseBath = $FactorUseBath;
$this->FactorNumberBath = $FactorNumberBath;
}
public function calcMethod() {
$result = $this->DurationOfBathing * $this->FactorUseBath * $this->FactorNumberBath * $this->NumberOfPeople;
return $result;
}
}